We describe an experiment in which a train of femtosecond pulses is coupled into a photonic crystal fiber (PCF) by means of an offset pumping technique that can selectively excite either the mode LP01 or LP11 or LP21. The PCF presents a wide range of wavelengths in which the fundamental mode experiences normal dispersion, whereas LP11 and LP21 propagate in the anomalous dispersion regime, generating a supercontinuum based on the soliton fission mechanism. We find that the existence of a cut-off wavelength for the higher-order modes makes the spectral broadening asymmetrical. This latter effect is particularly dramatic in the case of the LP21 mode, in which, by using a pump wavelength slightly below cut-off, the spectral broadening occurs only on the blue side of the pump wavelength. Our experimental results are successfully compared to numerical solutions of the nonlinear Schrödinger equation.
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Titolo: | Supercontinuum generation by higher-order mode excitation in a photonic crystal fiber |
Autori: | |
Data di pubblicazione: | 2008 |
Rivista: | |
Abstract: | We describe an experiment in which a train of femtosecond pulses is coupled into a photonic crystal fiber (PCF) by means of an offset pumping technique that can selectively excite either the mode LP01 or LP11 or LP21. The PCF presents a wide range of wavelengths in which the fundamental mode experiences normal dispersion, whereas LP11 and LP21 propagate in the anomalous dispersion regime, generating a supercontinuum based on the soliton fission mechanism. We find that the existence of a cut-off wavelength for the higher-order modes makes the spectral broadening asymmetrical. This latter effect is particularly dramatic in the case of the LP21 mode, in which, by using a pump wavelength slightly below cut-off, the spectral broadening occurs only on the blue side of the pump wavelength. Our experimental results are successfully compared to numerical solutions of the nonlinear Schrödinger equation. |
Handle: | http://hdl.handle.net/11571/135252 |
Appare nelle tipologie: | 1.1 Articolo in rivista |